To make everything clear, we will configure static NAT in GNS3. Open your GNS3 and build a topology like this:

(IOS used: c2600-bin-mz.123-6f.bin but you can use other versions)

We should use 3 routers in this topology but I want to save some RAM and demonstrate how to ping from the loopback interface so I only use two :) Therefore we should configure the loopback interface of R0 as the source IP address and the fa0/0 interface of R0 as the “outgoing static NAT” address.

In this article we don’t use a host attached to R0 so if we want to test our NAT configuration we have to ping from R0’s loopback interface by using the ping extended command:

We can use the extended ping command by typing only “ping” at the privileged mode, specify the “target IP address” and type “y” at the “Extended commands” and specify the “source address or interface” at shown below:

To approve NAT works well we can disable static NAT with the following command